The invention relates in general to fuzes and detonators for munitions and in particular to the Insensitive Munitions (IM) compliance requirements for fuzes and detonators.
A primary explosive is an explosive that is extremely sensitive to stimuli such as impact, friction, heat, static electricity, or electromagnetic radiation. A relatively small amount of energy is required for initiation of a primary explosive. Primary explosives are often used in fuzes and detonators to trigger larger charges of less sensitive secondary explosives.
A major concern in the field of fuzing and detonators is the ability to meet the Insensitive Munitions (IM) compliance requirements. Specifically, stimuli such as bullets, fragments and shape charge impacts are difficult IM challenges for detonators and fuzes. In particular, the primary energetics or explosives in these items are sensitive to the IM stimuli and may initiate the complete energetic train of a munition in a high order detonation.
Detonators and fuzes are similar in design and may use the same or similar types of energetics to attain the high order reaction. Detonators and/or fuzes may use primary and secondary energetics to achieve the needed detonation reaction speeds/velocities. Examples of primary energetics are materials such as lead azide, lead styphnate, RDX and others. Examples of secondary energetics are materials such as PBX-9407, PBXN-5, PBXN-107, PBXN-109 and others. The primary energetics are more sensitive to impact stimuli than the secondary energetics.
FIG. 1 is a sectional view of a known grenade fuze assembly 10. Fuze assembly 10 includes a fuze body 12 with a striker lever 14 rotatably mounted thereon. A rotor assembly 16 including a firing pin 18 is rotatably mounted to body 12. A spring 20 torsionally biases rotor assembly 16 in a counterclockwise direction. Spring 20 causes firing pin 18 to rotate counterclockwise and impact primer 22. The impact of firing pin 18 ignites primer 22. Primer 22 initiates an energetics train 24 disposed in fuze body 12. Energetics train 24 includes a delay mix 26, lead styphnate 28, lead azide 30, and RDX 32.
The primer 22 initiates the delay mix 26. The delay mix 26 provides a time delay, for example, a few seconds, before the delay mix 26 initiates the lead styphnate 28. The lead styphnate 28 initiates the lead azide 30. The lead azide 30 initiates the RDX 32. The RDX 32 initiates the main charge (not shown) in the grenade, for example, Composition B.
FIG. 2 is a sectional view of a known detonator 40 having a case or housing 42, a shock tube or detonation cord 44, lead styphnate 46, lead azide 48 and RDX 50. The shock or detonation cord 44 initiates the energetic reaction by initiating the lead styphnate 46. The lead styphnate 46 initiates the lead azide 48. The lead azide 48 initiates the RDX 50. The RDX 50 initiates the main charge (not shown) which may be, for example, plastic explosives, shape charges or other explosives.
In the grenade fuze 10 and the detonator 40, the primary energetics are lead styphnate 28, 46, lead azide 30, 48 and RDX 32, 50. In the fuze 10, the percussion primer 22 is also a primary energetic. These primary energetics are sensitive to stimuli such as bullet, fragment and shape charge impact and are problematic for IM compliance.
A need exists for fuzes and detonators that are less sensitive to impacts than known fuzes and detonators.